To reduce the disco effect you might like to make four clusters of LEDs: two clusters on each heat sink. Basically, squish your groups of five together. Which will leave you with an extra RB.
Don't glue anything in place yet. I had a huge amount of help from some forum members in placing mine, and what I wound up with was completely different from what I started with.
Edit: in case you haven't seen it . . . Here's what happened to my LEDs when forum members chimed in:
http://www.canreef.com/vbulletin/showthread.php?t=89518